1. Field of Invention
This invention relates to a grommet. In particular, this invention relates to a grommet that engages around a wire harness to be mounted on an automobile, and is mounted in a through hole of an automobile body panel, and improves protection of the wire harness at a position where the wire harness passes through the hole, as well as improving waterproofness and dustproofness.
2. Description of Related Art
Conventionally, a grommet engages around a wire harness to be mounted to extend from an engine compartment to a passenger compartment of an automobile, and the grommet is mounted in a though hole in an automobile body panel that divides the engine compartment from the passenger compartment. Thus, the wire harness passing through the through hole is protected, and intrusion of water, dust and. sound from the engine compartment side to the passenger compartment side is prevented.
As the grommet described above, a so-called one motion grommet is provided. When the one motion grommet is simply pressed into the through hole in the automobile body panel from one side to the other, an automobile body engagement recessed portion provided on an outer peripheral surface of the grommet engages with an edge of the through hole.
As shown in FIG. 17, the above-described grommet 1 is provided with a small-diameter cylindrical portion 2, and a tapered portion 3 which extends from an end of the small-diameter portion 2. The tapered portion 3 is provided with an automobile body engagement recessed portion 4 around a larger diameter end. Both side walls facing each other across a groove 4a of the automobile body engagement recessed portion 4 include a vertical wall 4b at the larger diameter side and an inclined wall 4c at a smaller diameter side. A wire harness W/H (FIG. 18) is inserted into a hollow portion extending from the small-diameter cylindrical portion 2 to the tapered portion 3 of the above-described grommet 1, and the grommet 1 is fixed with the wire harness W/H using a tape T at an end of the small-diameter cylindrical portion.
As shown in FIG. 18, during a mounting operation of the grommet 1 into the through hole H of the automobile body panel P, the grommet 1 is inserted into the through hole H from the small-diameter cylindrical portion 2, and the inclined wall 4c is pressed inwardly and deformed to pass through the through hole 4. Then, the inclined wall 4c, which recovers its original shape after passing through the through hole H, and the vertical wall 4b are tightly pressed into contact with both surfaces of the automobile panel P, respectively. Thus, the automobile body engagement recessed portion 4 of the grommet 1 engages with the through hole H of the automobile body panel P.
However, as shown in FIGS. 19(A) and 19(B), when the one motion grommet 1 is inserted into the through hole H so as to be inclined, one side of the tapered portion 3 is pressed excessively, and thus, an outer peripheral surface of a thin portion of the tapered portion 3, extending to the inclined wall 4c of the automobile body engagement recessed portion 4, is deformed inwardly. The inclined wall 4c, which must be bend inwardly, is bent and warped (flipped over) outwardly, and the inclined wall 4c touches the automobile body panel P. Thus, the grommet is prevented from passing through the through hole H.
When the grommet 1 is inserted straight so that the center axis of the grommet 1 is aligned with the center of the through hole H, the above-described problem does not occur. However, during the insertion operation of the grommet 1 into the through hole, it is sometimes difficult to insert the grommet 1 into the through hole straight, because of the restriction on a space. Thus, in many cases, the grommet is inserted in an inclining posture.
Further, if the tapered portion of the grommet 1 is thick so as to be incapable of being bent, the above-described problem is resolved to a certain extent. However, in that case, an insertion force required to insert the grommet into the through hole become larger.
On the other hand, if the tapered portion is too thin, since the stiffness of the tapered portion becomes small, and thus, the tapered portion becomes easily extended while the inserting operation is performed, an insertion stroke becomes long.
Accordingly, the present invention is provided in view of the above-described problems, and an objective of the present invention is to prevent the insertion force from being too large, and to enable a grommet to be mounted into a through hole of an automobile panel, even if the grommet is inserted in an inclining posture, and to reduce extension of the grommet at the time of insertion into the through hole and thus, to shorten the insertion stroke.
To achieve the above and/or other goals, the present invention provides a grommet configured to engage around an outer periphery of a wire harness and to be mounted in a through hole of an automobile body panel. The grommet includes a generally cylindrical portion, a tapered portion extending from one end of the generally cylindrical portion and a plurality of projecting strip portions provided on an outer peripheral surface of the tapered portion. The tapered portion includes an automobile body engagement recessed portion provided on an outer peripheral surface of the tapered portion to engage with the automobile body panel. The plurality of projecting strip portions extend in an axial direction of the tapered portion and are spaced from each other in a circumferential direction, A projection amount of the plurality of projecting strip portions is changed at a point in the axial direction so that a first projection amount between the contact point and a large diameter side end of the plurality of projecting strip portions is smaller than a second projection amount of the plurality of projecting strip portions between the contact point and a small diameter side end of the plurality of projecting strip portions. The above-described contact point is located substantially at a position where an outer surface of the plurality of projecting strip portions first contacts an inner peripheral surface of the through hole when the grommet is inserted into the through hole from the end of the grommet having the generally cylindrical portion.
Preferably, the grommet is made of a suitable elastic material, such as an elastic or an elastomer, similar to the conventional grommet.
If the projecting strip portions that extend in an axial direction and spaced from each other in a circumferential direction are provided on the outer peripheral surface of the tapered portion of the grommet, when the grommet is inserted in an inclining posture, first, the projecting strip portions touch the inner peripheral surface of the through hole. Accordingly, the operator can recognize the inclined insertion and can reinsert the grommet in a straight manner.
The above-described automobile body engagement portion can include a vertical wall at a large diameter end side of the tapered portion, and an inclined wall that faces the vertical wall across a groove. The inclined wall is bent inwardly to enable the grommet to pass through the through hole.
Preferably, the projecting strip portions provided on the outer peripheral surface of the tapered portion extend between an end connecting to the generally cylindrical portion to an edge of the inclined wall of the above-described automobile body engagement recessed portion.
As described above, if the projecting strip portions are provided on the outer peripheral surface of the taper end portion, the tapered portion is strengthened (reinforced). When the grommet is inserted in an inclining posture, the phenomenon in which the thin tapered portion extending to the inclined wall of the automobile body engagement recessed portion is warped outwardly (flipped over) at the side contacting the inner peripheral surface of the through hole, does not occur. Accordingly, the problem that occurred at the time of inclined insertion in the conventional grommet can be obviated.
Thus, the projection amount of the above-described projecting strip portions is changed at a contact point where the projecting strip portions contact an inner peripheral surface of the through hole during the insertion into the through hole, so that the projection amount between the contact point and a large diameter side end of the projecting strip portions becomes small.
Accordingly, when the grommet is inserted in the through hole of the automobile body panel, since the projection amount of the projecting strip portions changes, a tactile sensation is generated when the contact point reaches the panel position. From this contact point, the inclined wall must be pressed to be bent inwardly. Thus, from the time when the tactile sensation is generated, if the operator increases the force to press the grommet into the through hole without stopping, the inserting operation of the grommet into the through hole becomes efficient. In addition, since the projection amount of the projecting strip portions becomes small from the contact point, the inserting force can be reduced.
Preferably, an outer surface of the plurality of the projecting strip portion has an arced shape between the contact point and the large diameter side end, i.e., the edge of the inclined wall of the automobile body engagement recessed portion.
As described above, if the arced shape is formed between the contact point and the edge of the inclined wall of the automobile body engagement recessed portion, the grommet can be pressed toward and inserted into the through hole smoothly along the inner peripheral surface of the through hole. Accordingly, the tactile feel at the time of operation can be improved.
Instead of the arc, an outer peripheral surface of the plurality of projecting strip portions can be bent at the point so as to have different inclination angles.
In addition, preferably, the outer surface of the plurality of projecting strip portions extends parallel to the axial direction from a position where a height of the plurality of projecting strip portions from an axis of the grommet becomes equal to a height of an edge of a small-diameter-side (second side) wall of the automobile body engagement recessed portion.
In other words, the outer surface of the projecting strip portion that changes the inclination angle at the contact point, further changes the inclination angle at the position where the height thereof (from the axis of the grommet) become the same as that of the edge of the inclined wall. In other words, the projection amount of the projecting strip portion is gradually decreased. Thus, the inclination angle of the outer surface of the projecting strip portion with the axis changes at three levels. At the small diameter cylindrical side, the inclination angle is the largest. At the contact point, the inclination angle is decreased. Further, when the height of the outer surface of the projecting strip portion (from the axis) becomes the same as that of the edge of the inclined wall, the inclination angle is set to 0. Accordingly, both the correction of the inclination and the reduction of the inserting force into the through hole can be achieved.
According to the another aspect of the present invention, a grommet configured to engage around an outer periphery of a wire harness and to be mounted in a through hole of an automobile body panel is further provided. The grommet includes a generally cylindrical portion, a tapered portion extending from one end of the generally cylindrical portion, and a plurality of inner projecting strip portions provided on an inner peripheral surface of the tapered portion. The tapered portion includes an automobile body engagement recessed portion provided on an outer peripheral surface of the tapered portion to engage with the automobile body panel. The plurality of inner projecting strip portions extend in an axial direction of the tapered portion and are spaced from each other in a circumferential direction.
As described above, if the inner projecting strip portions are provided on the inner peripheral surface of the tapered portion, the stiffness of the grommet can be increased to a certain degree by which an excessive extension of the tapered portion does not occur during the grommet insertion operation into the through hole, and a flipped-over (warp) condition of the grommet at the time of the inclined insertion does not occur. In addition, the insertion stroke can be reduced. Further, since the inner projecting strip portions provided on the inner peripheral surface of the tapered portion extend in the axial direction, the action of the tapered portion reducing the diameter thereof is not prevented at the time of the inserting operation. On the contrary, the inner projecting strip portions works to equally reduce the diameter of the tapered portion toward the center thereof.
The grommet can further includes a plurality of outer projecting strip portions provided on an outer peripheral surface of the tapered portion. The plurality of outer projecting strip portions extend in an axial direction of the tapered portion and are spaced from each other in a circumferential direction. The plurality of outer projecting strip portions are located opposite the plurality of inner projecting strip portions.
A projection amount of the plurality of outer projecting strip portions is changed at a contact point in the axial direction so that the projection amount between the contact point and a large diameter side end of the plurality of outer projecting strip portions is smaller than a second projection amount of the plurality of outer projecting strip portions between the contact point and a small diameter side end of the plurality of outer projecting strip portions. The above-described contact point is located substantially at a position where an outer surface of the plurality of projecting strip portions first contacts an inner peripheral surface of the through hole when the grommet is inserted into the through hole from the generally cylindrical portion.
Preferably, the outer projecting strip portions provided on the outer peripheral surface of the tapered portion extend between a connection end, which connects to the generally cylindrical portion and the edge of the inclined wall of the automobile body engagement recessed portion.
As described above, when the outer projecting strip portions are provided on the outer peripheral surface of the grommet, and when the grommet is inserted in an inclining posture, first, the outer projecting strip portions touch the inner peripheral surface of the through hole. Accordingly, the operator can recognize the inclined insertion, and reinsert the grommet in a straight condition.
Further, if the outer projecting strip portions are provided on the outer peripheral surface of the tapered portion as well as the inner projecting strip portions provided on the inner peripheral surface of the tapered portion, when the grommet is inserted in an inclining posture, the phenomenon in which the thin tapered portion extending to the inclined wall of the automobile body engagement recessed portion is warped outwardly (flipped over) at the side contacting the inner peripheral surface of the through hole, does not occur. Accordingly, the problem that occurred at the time of inclined insertion in the conventional grommet can be obviated.
In particular, even if the height of the outer projecting strip portions provided on the outer peripheral surface of the tapered portion is small, the inner projecting strip portions are provided on the inner peripheral surface of the tapered portion opposite the outer projecting strip portions. Thus, the combined thickness of the outer projecting strip portions and the inner projecting strip portions is large, and the required reinforcement can be obtained. Accordingly, the height of the outer projecting strip portions provided on the outer peripheral surface of the tapered portion can be small, and thus, the profile of the entire grommet is prevented from being larger.